IMBerzerk Posted May 1, 2020 Share Posted May 1, 2020 I have to say I respect that you are really deep in this. It's great to see guys being able to troubleshoot shoot to this level! As far as repairing it.. if you get to a point that individual parts are hard to find, I have 2 spare power boards and I'd be happy to part with one. But I won't sway you. I know what it's like to wire worm stuff and want to stick with it till it fixed. Good on you! Keep going! 1 Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 1, 2020 Author Share Posted May 1, 2020 52 minutes ago, IMBerzerk said: I have to say I respect that you are really deep in this. It's great to see guys being able to troubleshoot shoot to this level! As far as repairing it.. if you get to a point that individual parts are hard to find, I have 2 spare power boards and I'd be happy to part with one. But I won't sway you. I know what it's like to wire worm stuff and want to stick with it till it fixed. Good on you! Keep going! Thanks I'll let you know if I need to get one or if I get it fix ! Quote Link to comment Share on other sites More sharing options...
IMBerzerk Posted May 1, 2020 Share Posted May 1, 2020 Yes, please keep posting the results. You're both on to something that has troubled these units for years. Can't tell you how many people have posted the same issues over the years only to give up... Myself included. Aside from the obvious transistor and capacitor swaps, it was always done by visual and hope to find the problem. New info, new ideas yields new results! 1 Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 1, 2020 Share Posted May 1, 2020 (edited) Well I don't like shotgunning the parts, especially if they test good. Unfortunately, analog electronics get tricky to diagnose because a problem created by one bad part can show up in a different circuit entirely. If anything, I'd suggest ordering a resistor in the 200-ohm 2W range, or 4 1K resistors and doing as I suggested above, if you're going to order parts. This would give an idea of whether the board/transformer are too aggressive or if the logic board isn't pulling hard enough. If the leads of the resistor(s) aren't long enough, you may also need to get some small alligator clips to connect them for the test. And to be more precise with a previous question: Have you reflowed the solder on the entire power supply board? Edited May 1, 2020 by ChildOfCv Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 1, 2020 Author Share Posted May 1, 2020 41 minutes ago, ChildOfCv said: Well I don't like shotgunning the parts, especially if they test good. Unfortunately, analog electronics get tricky to diagnose because a problem created by one bad part can show up in a different circuit entirely. If anything, I'd suggest ordering a resistor in the 200-ohm 2W range, or 4 1K resistors and doing as I suggested above, if you're going to order parts. This would give an idea of whether the board/transformer are too aggressive or if the logic board isn't pulling hard enough. If the leads of the resistor(s) aren't long enough, you may also need to get some small alligator clips to connect them for the test. And to be more precise with a previous question: Have you reflowed the solder on the entire power supply board? No I haven't resolderd the whole powder supply. Also I just soldered in a socket for the 7407 chip so I can take it out easily. But I will try to re solder the parts Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 1, 2020 Author Share Posted May 1, 2020 Ok yah I got some 1 k resistors now what sold I do Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 2, 2020 Share Posted May 2, 2020 7 hours ago, kevincondrick@gmail.com said: Ok yah I got some 1 k resistors now what sold I do On 4/30/2020 at 5:35 PM, ChildOfCv said: bundle the 1st leg of each resistor together, then do the same for the other leg, so that it should be about 250 ohms total. Connect those across the smaller capacitor and unplug the logic board, but leave the transformer plugged in. Measure the voltage across the capacitor. 1 Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 2, 2020 Share Posted May 2, 2020 13 hours ago, IMBerzerk said: Yes, please keep posting the results. You're both on to something that has troubled these units for years. Are you talking about the hot transistors issue? Sounds like at least one other system out there has the same problem. But if it's systemic, then maybe it's not a problem with this particular board. Instead, maybe you'd have to find the trace that connects the smaller of the two large capacitors to the 3rd pin on the ribbon cable connector, cut it, and solder a resistor between the two sides to provide some relief to the transistor circuit. 1 Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 2, 2020 Author Share Posted May 2, 2020 (edited) 7 hours ago, ChildOfCv said: Do you know what the residents rating is on that big resistor (R2) on the supply board? If so maybe I'll try changing it out if I have the right size resistor. Also I'm pretty sure it was making continuity between the 2 legs cuz at first I thought it was a fuse and I tested it as on and yah it was making continuity. So I have a feeling that it's either gonn bad or just has a really low residents level. Edited May 2, 2020 by kevincondrick@gmail.com Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted May 2, 2020 Share Posted May 2, 2020 2 hours ago, kevincondrick@gmail.com said: Do you know what the residents rating is on that big resistor (R2) on the supply board? If so maybe I'll try changing it out if I have the right size resistor. Also I'm pretty sure it was making continuity between the 2 legs cuz at first I thought it was a fuse and I tested it as on and yah it was making continuity. So I have a feeling that it's either gonn bad or just has a really low residents level. If you are talking about the large resistor on the power board, that is a 12ohm. Cap kits I buy have the option to add a 12ohm 3watt replacement for the originals. Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 2, 2020 Author Share Posted May 2, 2020 15 minutes ago, -^CrossBow^- said: If you are talking about the large resistor on the power board, that is a 12ohm. Cap kits I buy have the option to add a 12ohm 3watt replacement for the originals. Thanks I do have some resisters I'll just use one of them Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 2, 2020 Share Posted May 2, 2020 6 hours ago, kevincondrick@gmail.com said: Thanks I do have some resisters I'll just use one of them But also check the resistance in ohms mode. If it's about 12 ohms, that will beep the continuity tester, but it's still the correct resistance and does not indicate a short. Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 3, 2020 Author Share Posted May 3, 2020 2 hours ago, ChildOfCv said: But also check the resistance in ohms mode. If it's about 12 ohms, that will beep the continuity tester, but it's still the correct resistance and does not indicate a short. Ok yah I did check it was 13 ohms Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 3, 2020 Share Posted May 3, 2020 1 minute ago, kevincondrick@gmail.com said: Ok yah I did check it was 13 ohms That's an acceptable value. Plus, that resistor feeds the 5.6V to the STIC VCC, so unless something is going weird over there you're probably okay. Well, with the ribbon cable connected, check the voltage on both sides of that resistor. I guess we can also figure out if the STIC is getting proper voltage. It should be about 5.6V on one side (the output to the logic board) and higher on the other side. Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 3, 2020 Author Share Posted May 3, 2020 33 minutes ago, ChildOfCv said: That's an acceptable value. Plus, that resistor feeds the 5.6V to the STIC VCC, so unless something is going weird over there you're probably okay. Well, with the ribbon cable connected, check the voltage on both sides of that resistor. I guess we can also figure out if the STIC is getting proper voltage. It should be about 5.6V on one side (the output to the logic board) and higher on the other side. Well that seams to be ok . Iv notice that the CP was getting warm but idk if it's from the transistors or if it's bad voltage Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 3, 2020 Author Share Posted May 3, 2020 (edited) Also I took the negative lead off the 2200 cap and now I get the 16 v from the positive of the cap to ground Edited May 3, 2020 by kevincondrick@gmail.com Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 3, 2020 Share Posted May 3, 2020 3 hours ago, kevincondrick@gmail.com said: Iv notice that the CP was getting warm but idk if it's from the transistors or if it's bad voltage CP? You mean the capacitor? It shouldn't be getting warm. That usually means leakage, though in this case a little bit of leakage would help. Is there any residue on the PCB where the capacitor was? Were you able to try the resistor loading test? 2 hours ago, kevincondrick@gmail.com said: Also I took the negative lead off the 2200 cap and now I get the 16 v from the positive of the cap to ground That makes sense. The capacitor is there to smooth the AC power. When the input is 17.1V, it reaches a peak voltage through the bridge rectifier of 23V. Just like filling a sink, if the capacitor is being filled by the source current but nothing is taking it, the "sink" will fill up at 23V. When the logic board is pulling power, that is supposed to keep it down to 18V or less. But with no "sink" at all, the voltage will jump up and down from 0 to 23V. The DC meter will average it out, which seems to read about 16V. But if you switch to AC and take the same reading, it will also be about 16V. Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 3, 2020 Author Share Posted May 3, 2020 (edited) 7 hours ago, ChildOfCv said: CP? You mean the capacitor? It shouldn't be getting warm. That usually means leakage, though in this case a little bit of leakage would help. Is there any residue on the PCB where the capacitor was? Were you able to try the resistor loading test? That makes sense. The capacitor is there to smooth the AC power. When the input is 17.1V, it reaches a peak voltage through the bridge rectifier of 23V. Just like filling a sink, if the capacitor is being filled by the source current but nothing is taking it, the "sink" will fill up at 23V. When the logic board is pulling power, that is supposed to keep it down to 18V or less. But with no "sink" at all, the voltage will jump up and down from 0 to 23V. The DC meter will average it out, which seems to read about 16V. But if you switch to AC and take the same reading, it will also be about 16V. No I haven't tryed it yet because like idk what to do like you want me to put the resistors from one end of the cap to the other? Also I wouldn't know how to test it. The CP chip (cpu) I noticed it was getting fairly warm when I have that all plugged in. For testing this all I got it all unplugged. We will figure this out alittl at a time!! Edited May 3, 2020 by kevincondrick@gmail.com Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 3, 2020 Share Posted May 3, 2020 9 hours ago, kevincondrick@gmail.com said: No I haven't tryed it yet because like idk what to do like you want me to put the resistors from one end of the cap to the other? Also I wouldn't know how to test it. Yes, that's what I described. Roll them together so that it's one massive resistor. The reason for that is to increase the power handling of the bunch while making a 250-ohm load. So twist all 4 leads of one side of each resistor together. Twist all 4 leads of the other side of the resistor together. Now connect a lead to one side of the capacitor and one lead to the other side of the capacitor. Now put the black lead on the "-" side of the capacitor and the red lead on the other side, and take a DC voltage reading. That's why I suggested that alligator clips could help. Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 3, 2020 Author Share Posted May 3, 2020 55 minutes ago, ChildOfCv said: Yes, that's what I described. Roll them together so that it's one massive resistor. The reason for that is to increase the power handling of the bunch while making a 250-ohm load. So twist all 4 leads of one side of each resistor together. Twist all 4 leads of the other side of the resistor together. Now connect a lead to one side of the capacitor and one lead to the other side of the capacitor. Now put the black lead on the "-" side of the capacitor and the red lead on the other side, and take a DC voltage reading. That's why I suggested that alligator clips could help. Ok this is what I did I got like 3.97 ohm on just the resistors. Then with it on the cap it still comes up with 23.2 v I also noticed that c5 was missing. Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 4, 2020 Share Posted May 4, 2020 That was end-to-end connection though. I wanted all 4 of one side connected together, then all 4 of the other side connected together. I wish I could find a good image of the actual resistors together like that, but at least this image should give an idea of the difference. I'm talking about the parallel side. Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 4, 2020 Author Share Posted May 4, 2020 (edited) Oo ok I see Edited May 4, 2020 by kevincondrick@gmail.com Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 4, 2020 Author Share Posted May 4, 2020 Like this Quote Link to comment Share on other sites More sharing options...
kevincondrick@gmail.com Posted May 4, 2020 Author Share Posted May 4, 2020 1 minute ago, kevincondrick@gmail.com said: Like this The voltage is still pretty high it's 22.3 Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted May 4, 2020 Share Posted May 4, 2020 (edited) 2 minutes ago, kevincondrick@gmail.com said: Like this Edit: Oops, I just saw you included the voltage. Yeah that's really high. The transformer may be a little too eager with its power. But actually, this bodge may help. Read the voltage again with the logic board connected, and let's see if the voltage finally falls into an acceptable level Edited May 4, 2020 by ChildOfCv Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.